ORA2 release-2014-06-23T13.19

@stephensanchez Please review.  I've removed the algorithm config because of https://github.com/edx/edx-ora2/pull/451

@clytwynec This will need to be in the release candidate for this week.  This includes the "AI grading" feature we're dark-launching, which will require several database migrations.  I believe these migrations are additive (just adding new database tables), so the risk should be low.